This application claims the priority of German application 198 33 445.1, filed in Germany Jul. 24, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a disk brake for rail vehicles with an actuating device that has a lever on one or both sides of a rub ring, said lever being designed to transfer the deflections of an (especially hydraulically) actuated braking force generator on a pressure element to actuate at least one brake pad, with the pressure element being pivotably mounted on a rotational axis on the lever, and with at least one guide slot between an at least approximately fixed part of the disk brake and the pressure element, ensuring a largely fixed alignment of the pressure element as well as the brake pad relative to the rub ring.
A disk brake of this type is known from European Patent Document EP 0 731 286 A 1. The disk brake shown in this document, which is provided, however, for pneumatic actuation, is provided with a guide slot to avoid radial diagonal wear of at least one brake pad which is pivotable to a limited degree around an axis that extends approximately in the circumferential direction of a rub ring at the center of friction. The guide slot is located at a distance from the pressure bearing, with the distance having at least one component that runs parallel to the alignment of the rub ring. The guide path and the corresponding sliding block are mounted on an essentially fixed part and also on the brake pad by means of a steering lever, with the slot path running essentially parallel to the axial direction of the rub ring. If the pressure bearing is guided for example by a forked lever on a circular path, the slot path is advantageously designed to be curved in the same way as the circular path. Radial diagonal wear is simply prevented by the slot guide.
The above design of the slot guide has proven itself in use. However, a design that is simplified further as much as possible remains desirable, which operates safely even with increasing wear of the brake. The goal of the invention is to achieve this result.
The invention achieves this goal by providing a disk brake for rail vehicles comprising: an actuating device which has a lever on at least one side of a rub ring, said lever being designed to transfer deflections of a hydraulically actuated braking force generator on a pressure element to actuate at least one brake pad, the pressure element being pivotably mounted on a pivotal axis on the lever, wherein a largely unchanged alignment of the pressure element as well as the brake pad relative to the rub ring is guaranteed by at least one slot guide between an at least approximately fixed part of the disk brake and the pressure element, and wherein the at least one slot guide has two pins which engage displaceably and offset with respect to one another in at least two slot path segments which are designed to be at least approximately in a shape of a section of a circular arc and each have different radii.
In contrast to the prior art referred to above, the at least one slot guide has two pins that engage displaceably and offset with respect to one another in two slot path sections which are designed to be at least approximately in the form of a segment of a circular arc and have different radii. Preferably, one of the circular arc segments extends essentially concentrically with respect to the lever arm movement.
The invention offers the particular advantage that the first slot or the first slot path segment and the corresponding pin is designed as a slider in a structurally simple fashion (especially without a steering arm) in such fashion that it essentially has the same radius as the lever for actuating the brake pad, so that the pin, regardless of the position of the lever, always guarantees the horizontal alignment of the pressure element or the parallel alignment of the pressure element with respect to the rub ring. As a result, in the case of a new brake pad, in other words one that is not yet worn, pivoting of the pressure element around its rotational axis at the lever is reliably prevented.
The second slot with a different radius and another pin also counteracts the effect that the effective lever arm of the first pin or of the first slot guide becomes increasingly smaller as the lever pivots further inward. With considerable wear of the brake lining, the first pin has practically no further effect. At this point, however, the other slot guide or the other slot path section with the second pin S2 engages, which has a sufficient lever arm to the rotational axis of the brake pad. Thus, the function of the slot guide is guaranteed effectively in a structurally simplified and especially compact fashion even with increasing wear of the brake pads.
According to a preferred version of the invention, the slot path sections are designed as groove-shaped recesses in at least one guide plate. Preferably, the guide plate is fastened to the pressure element, with the slot guide path being aligned essentially parallel to the actuation of the brake pad. This version of the invention has the particular advantage that the necessity for designing a more complicated steering lever design for the slot guide is eliminated. It is merely necessary to manufacture the guide plates and to allow the pin to engage them.
According to certain especially preferred embodiment of the invention, one of the plates is fastened at each of the upper and lower ends of the pressure element, with the corresponding pins being formed on the brake caliper. As a result of the slot guide on the upper and lower ends and on the ends of the pressure element facing away from the lever, an especially secure slot guide is guaranteed.
In an alternative embodiment, it is also contemplated for the two slot path sections to be formed jointly in only one of the plates, so that the cost for making the slot guide is reduced further.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.